Automatic firearm



H. W. GABBETT-FAIRFAX.

AUTOMATIC FIREARVI.

APPLICATION FILED APII. 5. |920.

1,357,855?, Patented N0v.`2,1920.

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i., I I7 Patented Nov. 2, 1920.

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AUTOMATIC FIREARNI.

APPLICATION FILED APR. 5. 1920. 1,357,857.

Hl w. GABETT-FAIRFAX. AUTOMATIC FIREARM.

APPLICATION FILED APR 5 1920.

1,357,857, mma Nov. 2, 1920.

7 SHEETS-SHEET 3.

H. W. GABBETT-FAIRFAX.

AUTOMATIC FIREARM.

APPLICATION FILED APII. 5, 1920.

Patented Nov. 2, 1920.

7 SHEETS-SHEET 4.

H. W. GABBETT-FAIRFAX.

AUTOMATIC FIREARM.' APPLICATION HL'ED APR. 5. 1920.

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AUTOMATIC FIREARM.

APPLICATION FILED APR. 5l I920. 4

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'AUTOMATIC FIRE/IRM.

A APPLICATION FILED APR. 5, 1920. 15357385?, Patented N0v.2, 1920.

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. AUTOMATIC FIREARIVI.

Specification of Letters Patent.v

Application filed April 5,' 1920. Serial No. 371,545.

To all 'whom t may concern:

kprovements in Automatic Firearms, of

which the following is a specification.

ThisV invention relates to automatic or semi-automatic machine guns andsmallV arms of the kind in which the gun is operated by the shock ofrecoil, and in which the breech-block, barrel and bolt recoil whilefirmly locked together and remain in such relative position during thewholey period of recoil or for a considerable part of that period, afterwhich the bolt is unlocked and remains stationary or completes itsbackward movement while the barrel returns to its forward position ofrest. rlhe object of the present invention is to provide a simplifiedconstruction together with greater certainty and safety in operation offirearms working on the above principle.

According to this invention the bolt is capable of a limited rotation ina sleeve and has a radial arm controlled and operated by akreciprocating cam plate which is automatically locked to and unlockedfrom the bolt sleeve as required, a stop or detent serving to time thereturnmotion of the cam plate.

during the reciprocating motion of the bolt in a slot in the stationaryframework of the gun so thatit may only be free to rotate during thelocking or unlocking ofthe breech. A further feature of the inventioncomprises two independent spring controlled drums connectedv by means ofchains or other flexible connections to the breech sleeve and cam platerespectively for returning the recoiling parts to their initialposition.

by spring stops carried in a frame attached l to one or other of therecoiling parts is or are provided for feeding the cartridges.

The radial arm of the bolt may be.

This construction allows ofV delaying the closing of the breech till theIn the accompanying drawings :-V

.Figures 1 and l, read together, are a gitudinal section of a firearm inwhich the barrel and bolt are locked together during the whole period ofrecoil, and having my improvements applied thereto, the breech beingshown open.-

Figs. 2 and2a, read together, are a4 plan view of the same. l

Fig. 3 is a side elevation of the breech end of a firearm showing thecam plate for operating the breech bolt with one form of -detents andtripping plate hereinafter described, the breech being closed.

Fig. 4 is a cross section taken on the line 4 4, Fig. 2, to show oneform of spring control.

Fig. 5 is a cross section through the feed drums on the line 5 5, Fig.l, showing a method of producing rotation in one direction.

L* ig. 6 is a section taken on the line 6 6, Fig. 2. l

Fig. 7 is a side elevation showing a trip plate and cam platehereinafter described.

Fig. 8 is a section through the trip plate and cam plate, and is similarto Fig. 6 butl showing the parts in a second position.

Fig. 9 is arear view of the cam plate showing a Vstop hereinafterdescribed, and

Fig. 10 is another view showing the stop in its disengaged position.

Like letters and note corresponding' parts in the several figures.

ln these drawings, A is a cam plate which slides on a guideway 10 formedin or on one of the side plates L of the gun so that it has a restrictedreciprocating motion, and is intermittently connectedwith anddisconnected from the bolt sleeve B or, if desired, with*V and from thebolt C, and acts on .an arm which is rigidly connected to or is integralwith'tlie bolt C. The cam plate A. has a cam slot E in which the boltarm D works,l

and the cam plate is shown capable of being temporarily connected to anddisconnected from the bolt .sleeve B bv means of a spring locking boltor pinH. Relative motion between the cam plate and bolt sleeve causesrotation of the bolt C limited by the length of the slot. Alternativelythe .end of the radial arm D may be made to move in a fixed longitudinalslot in the framework, be-

Patented Nov. a, ieee.

lon-

figures of reference cleing free to rotate only when the boltis drivenhome in the breech, thus preventing relative motion of the cam plate andbolt sleeve except when actually required, and dispensing with thelocking bolt H.

The barrel J is carried in the breech sleeve or body K which is mountedin vsuitable guideways 12 inthe side plates L, L in which the breechsleeve or body slides when the recoil takes place. Atthe end of therecoil the barrel is brought to rest by the spring buffer M, and anotherspring buffer N Vchecks the barrel when it is returned'to its initialforwardposition.

A chain O is connected at one end to the breech sleeve and at the other'end to a drum P (see Fig. 2a). Said drum is controlled by a spring Q(Fig. Ll) which is either coiled or uncoiled, as preferred, when thechain is drawn backward bythe recoil of the breech sleeve,. and theenergy thus stored in the spring is used to return the breech sleeve toits initial position after the recoil is completed, besides serving tocheck the recoil. A similar arrangement of a chain R connected at oneend to the cam plate A and at the other to a drum S which is controlledby a spring T (Fig. 1-) serves to return the cam plate after the barrelhas gone forward. The drums P and S arevcapable of rotationindependently of each other. By this construction the use of longhelical springs for returning the bolt and barrel is avoided. It isdesirable that there should be a fieXible connection between the camplate A or breech end and its respective spring-controlled drum such asby wire rope or by the chain described above, but the connectionrmay beobtained by the use of linked yarms spring-controlled, if desired.

A stop V (F igs. 3, 9 and 10) is provided which holds back the cam plateA against the pull of the spring T until said stop is tripped by thefeeding of the next cartridge into place readyfor loading into thebreech. The stop V can rotate in the bracket shown in Figs. 3 and 9, and`is normally held against the side plate by the torsional energy storedin the helical spring indicated in Fig. 3. It is also capable of a shortforward movement when struck by the advanc- :ing cam plate, thus forminga spring buffer.

When the next cartridge is fed up the nose of the bullet depresses aplunger' V which acts through a bell crank lever V2, rod V3 and lever V4to lift the forward end of the :lever V5, thus forcing down the rearwardend of said lever and rotating the tail lever V6 whichV is integral withor rigidly attached to the stop V. This swings the head of the stop Vout of engagement with the cam plate A and frees the latter as shown inFig. 10. The cam plate A by itsrearward motion pushes the stop V asideby means of its inclined heel 31 (Figs. 3 and 7 and passes over the saidstop which rises behind the breech. The locking bolt H as shown inf.

Figs. 2, 6Y and 8, consists of a pin working vertically in a pocket A inthe cam plate and normally held down by the action of a spring so thatits lower end is pressed into a` recess H2 inthe bolt Sleeve` B. In thisposition the cam plate and bolt sleeve are locked together. The pin canbe raised clear of the recess by pressing on the tail of a trip lever H.In the forwardmotion of the bolt the tail of the lever H is depressed,as shown in Figs. 7 and 8, when passing under the tripplate W and the.pin is raised, thus unlock- When the cam plate A is drawn forward by thechain R (Figs. 2 andV 7) it forces the bolt-arm D to rotate in the camslot E, thus locking the bolt into the breech. The locking bolt H is nowrestingl on the top of the bolt sleeve B and it remains in such positionduring the recoil of the breech and bolt; but` when the cam plate isheld back against the stop V and the barrel and bolt-sleeve go forward,the locking bolt H will drop into the recess H2 as soon as the forwardtravel of the bolt sleeveB relatively to the cam plate C is complete,the unlocking of thel bolt from the breech taking place` during thisrela-tive movement. The cam plate A is then locked to the bolt sleeve Band both are drawn forward togetherv by the chain R as soon as the stopV is moved aside. Any suitable device which will perform the samelocking and unlocking function may be used.

The firearm is provided with feed drums X, X carrying a belt (see Figs.1 and 2) which brings the cartridges successively into correct positionfor the forward motion of the breech boltto sweep them successively outof the belt clips and into the cartridge chamber. The breech sleeve orbody K in returning to its initialV forward position rotates the feeddrums by means of spring pins Y, Y which are carried in a frame 13rigidly attached to the breech sleeve or body K, and which in thearrangement shown work in a series of inclined grooves 14 formed on thesurfaces of the drums which merge near each end into a second series oflgrooves 15 parallel to the axis of the drums. The said grooves 1,4, 15are of varying depth so that the spring pins Y, Y when passing from theinclined grooves to the axial grooves and also from the axial grooves tolng the cam Yplate from the bolt sleeve.

' the inclined grooves, drop from a groove of 5 with the minimum weight.

shallower to a groove of greater depth, thus preventing the studs fromretracing their paths and rotating the feed drums backward.

In the construction of the cross frames or diaphragme in the frameworkof a machine gun I prefer to use flitch plates Z, Z, the outer platebeing of metal andthe central plate of wood or other suitable' material.the object being to secure sufficient strength The firing mechanism 1sof the ordinary type consisting of a hammer 50, mainspring 51, and searor sears with a safety attachment, one sear being released automaticallyby the complete locking of the bolt. In the arrangement shown, the sear16 is released by the toe 30 of the cam plate A engaging with the triplever 17 and tripping the sear 16 (Fig. 2) through the train of links 40shown in Figs. 1 and 2. This en- `gagement occurs at the instant ofcomplete locking of the breech.

A second searV 1S may also be provided which is Ytripped by the pull ofthe trigger, thus permitting'of automatic bursts of fire, the durationof which is controllable by the operator. Y

In the arrangement shown, the piston 19 (Fig. 2) of a synchronizingapparatus is indicated by dotted lines, the apparatus being of theConstantinesco or ,any lother suitable type, and operating to hold thesear in engagement when necessary, by any suitablel .sans The piston asshown, and the synchronizing gear generally is only required when thegun is mounted in aircraft of the type in which the gun fires throughthe propeller. The piston acts by holding the sear 16 in engagementwhen, and only when, the blade ofthe propeller is passing before themuzzle of the gun. VThe re of the gun is thus prevented from damagingvthe propeller. A spring connection 20 (Fig. 1) is provided: at anyysuitable point in the train of levers operating the sear 16 so thatwhen the synchronizing piston is holding down the sear 16, the breechcan still close without damaging the synchronizer, or breaking thelinkwork.

ln cases in which the breech sleeveY and barrel recoil over the feedmechanism, it will usually be necessary to provide means for raising thecartridge into the proper position for the bolt to load it into thebreech after the breechsleeve has gone forward, the belt and cartridgesbeing at other times below the/level of the underside of the breechsleeve. carriage 21 is provided which carriage is held down below theclearance line lof the breech by the action of springs 24, but is raisedby the pull of a link N acting through a bell crank lever N2, the link Nbeing actuated by the spring buffer N when lor this purpose a lifting'reaching the end of its travel at such time as the breech sleeve andbarrel are reaching their initial position.

Any other suitable method 'may be employed for conveying thecartridgesto their proper position for loading, after the breech sleevehas gone forward.

A further function is performed by the lifting carriage as shown. Aslthe belt feeds across from one drum X to the other Vay cartridge cominginto position in a vertical plane through the aXis of the gun depressesthe plunger V which operates through bell crank V2 to push plunger V3 tothe rear. With plunger V3 in this position it comes into engagement withthe release lever V4 on the rise of the lifting carriage, and throughthe auxiliary lever V5 rotates the stop 2V and releases the cam plate.85

When an empty space occurs in the cartrid'gebelt, or when the lastcartridge is fired, the breech sleevel goes forward raising the liftingcarriage, but the plunger V3 has not been driven to the rear because theplunger V has not been depressed andthe plunger V3 is therefore, by theaction of its spring V7, held out of engagement with the lever V4.Consequently the cam plate is not released and the gun stops with thebreech open ready for the insertion Ofanother belt. The arrangement justdescribed is only one method of attaining the Iabove result, and anyother suitable mechanism ma be used.

he functioning is as follows t-Just before firing, Ithe breech sleeve Kis in its forward position with a cartridge in the chamber and the boltC closing the breechv and locked into it by locking lugs of the usualpattern. `The hammer is cocked, and the breech being closed the scar 16is tripped, but as the trigger rod connected to the sear 18 has not beenpulled the sear 18 is still in engagement, also as the barrel is 110forward, the spring buffer N is in its eX- treme forward position andhas raised the lifting carriage 2l by the pull of the link N. 0n pullingthe trigger rod, the scar 18 is tripped and the shot is fired. The shock115 of recoil drives back the barrel, mounted in the breech sleeve K andbolt C (which are locked together) against the action of the springs Qand T (fig. 4). The hammer is cocked by the recoil "of the bolt sleeveB. 120 The spring buffer N rotates vrearwardly actuated by its spring,and frees the link N which is drawn back by the action of the springs24,driving the lifting carriage 21 down to its normal position. Thisallows 125 the recoiling parts to travel over the top of the cartridgesand belt.

When the recoiling parts are liust being brought to rest by the springbuffer' M the inclined heel 31 of the cam plate treads 130 down andpasses over the sprin stop V which stop rises again in front o the camplate. On the completion of the recoil movement, the springs Q, and T(Fig. 4) assert themselves and draw the breech sleeve and cam plateslightly forward against the stop V. During the recoil, the

locking pin H has been out of engagement and when the cam plate reachesthe stop V left behind, retained against the Vface ofl the bolt by theextractor. During the recoil of the breech sleeve K the spring pins Y, Y(Fig. l5) travel in the axial grooves 15 in the feed drum X, X and norotation occurs, but in the forward movement of the breech the-springpins Y, Y travel in the inclined grooves 14 and rotate the feed drums7bringing the next cartridge into position in the vertical plane throughthe axis of the barrel. In the arrangement shownthe ejection occurstoward the end of the forward movement of the breech sleeve, but beforethe lifting carriage is raised.

As the barrel comes to rest, it drives forward the spring buffer N whichactua-.tes the rod N and raises the lifting carriage 2l bringing intothe loading position the cartridge which has just been fed up. Thiscartridge, in being carried by the belt into the vertical plane throughthe axis of the barrel, has depressed the plunger V and driven theplunger V3 to the rear, so that when the lifting carriage rises the tailof the plunger V3 engages with the lever V4 and rotates the stop V thusreleasing the cam plate A. Said cam plate is then drawn forward by theaction of the spring T (Fig. 4) and chain R, and carries the bolt sleevewith it, both being firmly locked together by the pin H. The cartridgewhich has just been lifted is carried forward and loaded into thebreech, and the head ofthe bolt C enters the breech.

W hen the travel of the bolt is completed, and it comes to rest againstthe base of the cartridge in the chamber, the lever H passes under thetripping plate W (Figs. 3 and 6) and the pin H is unlocked. This permitsthe cam plate to go forward relatively to the bolt sleeve, and the boltarm D is rotated in the slot E and locks the bolt. As the cam plate Acompletes its travel, its toe 30 actuates the lever 17 (Figs. 65

means for guiding said barrel, breech and breech-bolt so as to beslidable in said frame, a sleeve in which said bolt has a limitedfreedom of rotation, a radial arm on said bolt,` a cam-plate engagingsaid arm, means for reciprocating said cam-plate, means for locking andunlocking said cam-plate to and from said sleeve, and a detent forcontrolling the time of the return motion of said cam-plate.

2. A recoil-operated firearm comprising a frame, a barrel, a breech anda breech-bolt, means for guiding said barrel, breech and breech-bolt soas to be slidable in said frame, a sleeve in which said bolt has alimited freedom of rotation, a radial arm on said bolt, a cam-plateengaging said arm, means for reciprocating said cam-plate, means forlocking and unlocking said cam-plate to! and from said sleeve, a detentfor controlling the time of the return motion of said cam-plate', twoindependent spring-controlled drums, and flexible connections betweensaid drums and the breech sleeve and cam-plate respectively.

3. A recoil-operated firearm comprising a frame, a barrel, a breech, anda breech- Y ineans for reciprocating said cam-plate,-

means for locking and unlocking said camplate to and from said sleeve, adetent for controlling the time of the return motion of said cam-plate,spring buffers, and means for connecting said spring buffers and saidreciprocating parts. f

4. A recoil-operated firearm, comprising a frame, a barrel, a breech,and a breechbolt, means for guiding said barrel, breech and breech-bolt,so as to be slidable in said frame, a sleeve in which said bolt has alimited freedom of rotation, a radial arm on said bolt, a cam-plateengaging said arm, means for reciprocating said cam-plate, means forlocking and unlocking said camplate to and from said sleeve,va'detentfor controlling the time of the return motion of said cam-plate, groovedcartridge feed drums pivotally mounted in said frame, a frame attachedto one of said recoiling iio` parts, and spring stops carried by saidframe and adapted to actuate said feeddrums.

5. A recoil-operated firearm, comprising a frame, a barrel, a breech,and a breechbolt, means for guiding said barrel, breech and breech-bolt,so as to be slidable in said frame, a sleeve in Which said bolt has alimited freedom of rotation, a radial arm on said bolt, a cam-plateengaging said arm, means for reciprocating said cam-plate, means forlocking and unlocking said camplate to and from said sleeve, a detentfor controlling the time of the return motion of said cam-plate, andmechanism adapted to bring cartridges from a belt successively into linewith the axis of the gun for loading, and means for moving saidmechanism automatically out of the path of the recoiling breech.

6. A Vrecoil-operated firearm, comprising a frame, a barrel, a breech,and a breechbolt, means for guiding said barrel, breech and breech-bolt,so as to be slidable in said frame, a sleeve in which said bolt has alimited freedom of rotation, a radialarm on said bolt, a cam-plateengaging said arm,`

controlling the time of the return motionV of said cam-plate, a trigger,firing mechamsm comprislng tWo sears, an operative connection betweenone of said sears and the trigger, and an operative connection Y betweenthe other scar and the breech.

7 A recoil-operated firearm comprising a frame, a barrel, a breech and abreechbolt, means for guiding said barrel, breech and breech-bolt so asto be slidable in said frame, a sleeve in which said bolt has a limitedVfreedom of rotation, a radial arm on said bolt, a cam-plate engagingsaid arm, means for reciprocating said cam-plate, means for locking andunlocking said camplate to and from said sleeve, and means forperiodically preventing relative motion of said cam-plate andbolt-sleeve.

Dated this eleventh day of March, 1920.

E. S. W. ADAMS GEBBE.

